Can't close iOS in app browser on iPad

I use widow.open(Url) to open a PDF file. I have tried every permutation of that that I can find on this board from multiple threads and they have varying success, but when I use an iPad I can never get the inAppBrowser to allow me to close the PDF and go back to the application. Instead I must completely close the application. How do I fix this? How do I display the close or done button?